Hydrogen Bromide → 1H-Pyrazole-5-carboxylic acid, 3-bromo-1-(3-chloro-2-pyridinyl)-4,5-dihydro-, ethyl ester

Participants

Reaction Steps

Hydrogen bromide was passed through a solution of ethyl 1-(3-chloro-2-pyridinyl)-4,5-dihydro-3-[[(4-methylphenyl)sulfonyl]oxy]-1H-pyrazole-5-carboxylate (i.e. product of Step A) (5 g, 11.8 mmol) in dibromomethane (50 mL). After about 60 minutes the gas flow was terminated, and the reaction mixture was washed with aqueous sodium bicarbonate solution (50 mL). The organic phase was dried and evaporated under reduced pressure to give the title product as an oil (3.92 g, 100% yield), which crystallized on standing. The 1H NMR spectrum of the product was the same as reported for the product of Example 1, Step C.

Provenance & Evidence